Removal of Pb (II) and V (V) from aqueous solution by glutaraldehyde crosslinked chitosan and nanocomposites

In this paper, new adsorbents with high mechanical strength chitosan-graphene oxide (CS-GO) and chitosan-titanium dioxide (CS-TiO₂) were synthesized by using glutaraldehyde as crosslinking agent, and the adsorption behavior of Pb (II) and V (V) on them were investigated. The materials were characterized by scanning electron microscopy (SEM-EDS), Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). The effects of initial metal ion concentration and contact time on the removal of V (V) and Pb (II) by CS-GO and CS-TiO₂ were investigated. Characterization results showed that the hydroxyl group of GO/TiO₂ reacted with the amino group of chitosan. A comparison of the kinetic models against experimental data showed that the kinetics react system was best described by the pseudo-second-order model. indicating that chemical adsorption was the main adsorption force. the Langmuir adsorption model and Freundlich model agreed well with the experimental data. The removal capacity of Pb (II) by CS-GO and CS-TiO₂ were lower than those of V (V). The uncross-linked -OH and CO were the main adsorptive sites for Pb (II) removal, while uncross-linked -OH and -NH₂ played an important role in removing V (V). These findings provided insights on the removing lead and vanadium pollution.

Effect of the addition of fique bagasse microparticles in obtaining a biobased material based on cassava starch

The indiscriminate accumulation of plastic waste has prompted research that leads to obtaining biobased materials. The research aim was to evaluate the effect of incorporating fique bagasse microparticles (FBM) in a cassava starch-based foamed material. First, the FBM extraction conditions were established by acid hydrolysis, for which the effect of acid concentration (5, 10 and 15% H₂SO₄), temperature (70, 80 and 90 °C) and extraction time (3, 5 and 7 h) on particle size, functional groups, color, and thermal properties was evaluated. The addition of FBM to the foamed material was then carried out. To do this, a completely randomized design with five treatments (0, 0.5, 0.75, 1.0 and 1.25% FBM) was evaluated. The response variables were the apparent density, expansion and spring index, compressibility, water absorption, thermal properties and FTIR. The results showed that the acid concentration, temperature and time had an effect on the morphological, chemical and thermal properties of FBM, with 10%, 70 °C and 7 h being the conditions that allowed obtaining the smallest particle size (61.69 ± 12.88 μm²). Moreover, the FBM concentration had a significant effect on the physical and mechanical properties of the foam, unleashing the treatment properties of 0.75%. This indicates that FBM have potential for use in obtaining biobased materials.

Establishment of the basidiomycete Fomes fomentarius for the production of composite materials

Background

Filamentous fungi of the phylum Basidiomycota are considered as an attractive source for the biotechnological production of composite materials. The ability of many basidiomycetes to accept residual lignocellulosic plant biomass from agriculture and forestry such as straw, shives and sawdust as substrates and to bind and glue together these otherwise loose but reinforcing substrate particles into their mycelial network, makes them ideal candidates to produce biological composites to replace petroleum-based synthetic plastics and foams in the near future.

Results

Here, we describe for the first time the application potential of the tinder fungus Fomes fomentarius for lab-scale production of mycelium composites. We used fine, medium and coarse particle fractions of hemp shives and rapeseed straw to produce a set of diverse composite materials and show that the mechanical materials properties are dependent on the nature and particle size of the substrates. Compression tests and scanning electron microscopy were used to characterize composite material properties and to model their compression behaviour by numerical simulations. Their properties were compared amongst each other and with the benchmark expanded polystyrene (EPS), a petroleum-based foam used for thermal isolation in the construction industry. Our analyses uncovered that EPS shows an elastic modulus of 2.37 ± 0.17 MPa which is 4-times higher compared to the F. fomentarius composite materials whereas the compressive strength of 0.09 ± 0.003 MPa is in the range of the fungal composite material. However, when comparing the ability to take up compressive forces at higher strain values, the fungal composites performed better than EPS. Hemp-shive based composites were able to resist a compressive force of 0.2 MPa at 50% compression, rapeseed composites 0.3 MPa but EPS only 0.15 MPa.

Conclusion

The data obtained in this study suggest that F. fomentarius constitutes a promising cell factory for the future production of fungal composite materials with similar mechanical behaviour as synthetic foams such as EPS. Future work will focus on designing materials characteristics through optimizing substrate properties, cultivation conditions and by modulating growth and cell wall composition of F. fomentarius, i.e. factors that contribute on the meso- and microscale level to the composite behaviour.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40694-022-00133-y.

Preparation and applications of chitosan and cellulose composite materials

Chitosan is a natural fiber, chemically cellulose-like biopolymer, which is processed from chitin. Its use as a natural polymer is getting more attention because it is non-toxic, renewable, and biocompatible. However, its poor mechanical and thermal strength, particle size, and surface area restrict its industrial use. Consequently, to improve these properties, cellulose and/or inorganic nanoparticles have been used. This review discusses the recent progress of chitosan and cellulose composite materials, their preparation, and their applications in different industrial sectors. It also discusses the modification of chitosan and cellulose composite materials to allow their use on a large scale. Finally, the recent development of chitosan composite materials for drug delivery, food packaging, protective coatings, and wastewater treatment are discussed. The challenges and perspectives for future research are also considered. This review suggests that chitosan and cellulose nano-composite are promising, low-cost products for environmental remediation involving a simple production process.

Research progress of smart response composite hydrogels based on nanocellulose

In recent years, smart-responsive nanocellulose composite hydrogels have attracted extensive attention due to their unique porous substrate, hydrophilic properties, biocompatibility and stimulus responsiveness. At present, the research on smart response nanocellulose composite hydrogel mainly focuses on the selection of composite materials and the construction of internal chemical bonds. The common composite materials and connection methods used for preparation of smart response nanocellulose composite hydrogels are compared according to the different types of response sources such as temperature, pH and so on. The response mechanisms and the application prospects of different response types of nanocellulose composite hydrogels are summarized, and the transformation of internal ions, functional groups and chemical bonds, as well as the changes in mechanical properties such as modulus and strength are discussed. Finally, the shortcomings and application prospects of nanocellulose smart response composite hydrogels are summarized and prospected.

3D scaffold fabricated with composite material for cell culture and its derived platform for safety evaluation of drugs

In order to overcome the weakness of conventional approaches for cell culture, and provide cells with more in vivo-like microenvironment for studying hepatotoxicity of drugs, "multiple-in-one" strategy was adopted to fabricate a 3D scaffold of silk fibroin/hydroxyapatite/poly lacticco-glycolic acid (SF/HA/PLGA), where HepG2 cells were cultivated and the toxicity of drugs to the cells was investigated. The prepared 3D scaffold proves to bear proper porosity, excellent mechanical property, steady pH environment and good biocompatibility for cell culture. Furthermore, the validity of the developed 3D-SF/HA/PLGA-scaffold based platform was verified by probing the toxicity of a known drug-induced liver injury (DILI) concern acetaminophen (APAP) to HepG2 cells. Eventually, an application of the platform to dioscin (a medicinal plant extract) reveals the hepatotoxicity of dioscin, which involves the inhibition of the expression of CYP3A4 mRNA in the cells. The developed 3D-SF/HA/PLGA-scaffold platform may become a universal avenue for safety evaluation of drugs.

Physicochemical and biological properties of carboxymethyl chitosan zinc (CMCS-Zn)/α‑calcium sulfate hemihydrate (α-CSH) composites

To improve the osteoinductivity, antibacterial activity, and clinical application of calcium sulfate hemihydrate (CSH), carboxymethyl chitosan zinc (CMCS-Zn) and α-CSH were prepared using different mass ratios. The setting time and injectability of the CMCS-Zn/α-CSH composite were increased with increasing CMCS-Zn content. After adding different amounts of CMCS-Zn to α-CSH, the fine lamellar structure of CMCS-Zn was found by scanning electron microscopy (SEM), which is evenly distributed in the matrix of α-CSH. With the increase of CMCS-Zn, the pores on the surface gradually increased. After mixing CMCS-Zn and α-CSH, no new phase was measured by X-ray diffraction (XRD) and Fourier transform (FTIR) spectroscopy. The degradation rate of CMCS-Zn/α-CSH decreased with increasing CMCS-Zn content, and the pH was stable during the degradation process. The release of Zn²⁺ increased with increasing CMCS-Zn content, while the release of Ca²⁺ decreased. Extracts of CMCS-Zn/α-CSH composites up-regulated the osteoinduction and migration of rat bone marrow stem cells. The antibacterial ability of CMCS-Zn/α-CSH was evaluated as a function of CMCS-Zn content. In the rat bone defect model, 5% CMCS-Zn/α-CSH group revealed a higher volume and density of trabeculae by micro-CT 8 weeks after the operation. Therefore, CMCS-Zn/α-CSH was demonstrated to be an adjustable, degradable, substitute biomaterial (with osteogenesis-promoting effects) for use in bone defects, which also has antibacterial activity that can suppress bone infection.

Diffusion-controlled release of the theranostic protein-photosensitizer Azulitox from composite of Fmoc-Phenylalanine Fibrils encapsulated with BSA hydrogels

Hydrogels offer a promising potential for the encapsulation and regulated release of drugs due to their biocompatibility and their tunable properties as materials. Only a limited number of systems and procedures enable the encapsulation of sensitive proteins. N-terminally fmoc-protected phenylalanine has been shown to self-assemble into a transparent, stable hydrogel It can be considered a supergelator due to the low amount of monomers necessary for hydrogelation (0.1% w/v), making it a good candidate for the encapsulation and stabilization of sensitive proteins. However, application options for this hydrogel are rather limited to those of many other fibril-based materials due to its intrinsic lack of mechanical strength and high susceptibility to changes in environmental conditions. Here, we demonstrate that the stability of a fibrillary system and the resulting release of the protein-photosensitizer Azulitox can be increased by combining the hydrogel with a tightly cross-linked BSA hydrogel. Azulitox is known to display cell-penetrating properties, anti-proliferative activity and has a distinctive fluorescence. Confocal microscopy and fluorescence measurements verified the maintenance of all essential functions of the encapsulated protein. In contrast, the combination of fibrillary and protein hydrogel resulted in a significant stabilization of the matrix and an adjustable release pattern for encapsulated protein.

Applicability of composite materials for space radiation shielding of spacecraft

Energetic ion beam experiments with major space radiation elements, ¹H, ⁴He, ¹⁶O, ²⁸Si and ⁵⁶Fe, have been conducted to investigate the radiation shielding properties of composite materials. These materials are expected to be used for parts and fixtures of space vehicles due to both their mechanical strength and their space radiation shielding capabilities. Low Z materials containing hydrogen are effective for shielding protons and heavy ions due to their high stopping power and large fragmentation cross section per unit mass. The stopping power of the composite materials used in this work is intermediate between that of aluminum and polyethylene, which are typical structural and shielding materials used in space. The total charge-changing cross sections per unit mass, σ_UM, of the composite materials are 1.3-1.8 times larger than that of aluminum. By replacing conventional aluminum used for spacecraft with commercially available composite (carbon fiber / polyether ether ketone), it is expected that the shielding effect is increased by ∼17%. The utilization of composite materials will help mitigate the space radiation hazard on future deep space missions.

Controlled preparation of hollow Zn0.3Cd0.7S nanospheres modified by NiS1.97 nanosheets for superior photocatalytic hydrogen production

Developing durable and efficient photocatalysts for H₂ evolution is highly desirable to expedite current research on solar-chemical energy conversion. In this work, a novel photocatalytic H₂ evolution system based on Zn_0.3Cd_0.7S/NiS_1.97 nanocomposite was rationally designed for the first time. In this advanced composite structure, NiS_1.97 nanosheets as a co-catalyst were intimately coupled to the inner surface of the hollow spherical Zn_0.3Cd_0.7S. The construction of the hollow spherical shell shortened the distance of charge migration to the surface site and increased the multiple absorption of incident light. The introduction of NiS_1.97 nanosheets increased the light absorption capacity of the composite system and also greatly improved the separation and migration behavior of photo-generated carriers due to its narrower band gap and relatively low conduction band position, which had been confirmed by DRS, EIS and PL. As a result, the hollow Zn_0.3Cd_0.7S/NiS_1.97 composite material exhibited excellent photocatalytic activity. At the loading amount of NiS_1.97 up to 15 at.%, the hollow Zn_0.3Cd_0.7S/NiS_1.97 composite exhibited the best photocatalytic activity with a corresponding H₂ production rate of 22.637 mmol g^-1h^-1, which was 1.42 times and 1.85 times that of hollow Zn_0.3Cd_0.7S and solid Zn_0.3Cd_0.7S, respectively. Moreover, this novel catalyst also displayed a long-term stability without apparent debasement in H₂ evolution activity. It is expected that this work could provide new inspiration to the design and development of other highly active photocatalytic systems for water splitting.

Preparation, characterization, and catalytic activity of a novel MgO/expanded graphite for ozonation of Cu-EDTA

Magnesium oxide/expanded graphite (MgO/EG) catalyst was synthesized and applied for enhancing the degradation of Cu-ethylenediaminetetraacetic acid (Cu-EDTA) in an aqueous solution. The MgO/EG catalyst was characterized by XRD, SEM, EDS, and FTIR. For assessing the catalytic activity of MgO/EG, essential influencing factors were investigated including catalyst dosage, O₃ dosage, initial pH, initial Cu-EDTA concentration, and coexisting ions. The results show that the catalytic material showed high catalytic oxidation capacity for the Cu-EDTA removal in the MgO/EG/O₃ system. 100% of Cu(II) and 73.2% of TOC removal efficiency could be achieved in the MgO/EG/O₃ system at the reaction times of 90 min. This efficiency was higher than that seen for other systems, including O₃ alone (Cu(II) 81.4%/TOC 60.6%), EG/O₃ (84.2%/64.1), MgO/EG (< 4%/< 4%), and EG (< 4%/< 4%). A small decrease in the Cu(II) and TOC removal rate was observed after three runs in the stability and reusability experiments of the catalyst. Assays with radical scavenging experiments confirmed that MgO/EG-mediated oxidation was dependent on a hydroxyl radical pathway. The UV-vis spectra confirmed that the absorption peak of Cu-EDTA was gradually decreased and finally disappeared.

Disposable and low-cost electrochemical sensor based on the colorless nail polish and graphite composite material for tartrazine detection

A new method to manufacture electrochemical devices based on the graphite and colorless nail polish (N-grap) film was developed for tartrazine (Tz) detection. Scanning Electron Microscopy (SEM) demonstrates that the composite material presents a high porous carbon structure. Cyclic voltammetry (CV) and Electrochemical Impedance Spectroscopy (EIS) were employed to electrochemically characterize the electrode material, which corroborates the porous structure of the N-graph due to the enhanced electroactive area (5.4-fold increase) and presented a heterogeneous electron transfer rate constant (k0) of 5.82 × 10-3 cm s-1 for potassium ferricyanide. The electrochemical determination of the Tz was carried out using square-wave voltammetry (SWV), under the optimized experimental conditions, which showed high sensitivity (0.793 A L mol-1) and a lower limit of detection (LOD) of 2.10 × 10-8 mol L-1 with a linear concentration ranging from 2.0 to 50.0 μmol L-1. The developed sensor was applied for the analysis of Tz in sports drink samples and the result obtained by N-grap device was statistically compared with a spectrophotometric method demonstrating good accordance and the accuracy of the proposed method. Based on these results, we believe that this new fabrication method to produce disposable and low-cost electrochemical devices can be an alternative method for in-field analysis of dye in commercial sport drink samples and other relevant applications.

Efficient Removal of Cs+ and Sr2+ Ions by Granulous (Me2NH2)4/3(Me3NH)2/3Sn3S7·1.25H2O/Polyacrylonitrile Composite

The need to effectively and selectively remove radioactive ¹³⁷Cs and ⁹⁰Sr from nuclear waste solutions persists to mitigate their environmental mobility and high radiotoxicity. Because it is difficult to effectively remove them from acidic environments that degrade most sorbents, new sorbent materials are highly desirable. Here, efficient removal of Cs⁺ and Sr²⁺ is achieved by the composite of layered tin sulfide (Me₂NH₂)_4/3(Me₃NH)_2/3Sn₃S₇·1.25H₂O (FJSM-SnS) and polyacrylonitrile (PAN) (FJSM-SnS/PAN). The granulous composite possesses regular particle morphology and good mechanical strength as an engineered form. It shows excellent acid-base and γ-irradiation resistance, high maximum adsorption capacities (q_m) of 296.12 and 62.88 mg/g for Cs⁺ and Sr²⁺ ions, respectively, and high selectivity even in the presence of excess Na⁺ ions or using lake water. Impressively, q_m^Cs of FJSM-SnS/PAN reaches 89.29 mg/g under even acidic conditions (pH = 2.5). The column loaded with FJSM-SnS/PAN granules exhibits high removal rates (R) toward low-concentration Cs⁺ and Sr²⁺ ions under both neutral and acidic conditions. Moreover, the composite can be recycled and reused with high R^Cs and R^Sr. This work highlights the great potential of metal sulfide ion-exchangers in engineered form for the efficient removal of Cs⁺ or Sr²⁺ ions, especially under acidic conditions, for radionuclide remediation.

Activated carbon additives for technetium immobilization in bentonite-based engineered barriers for radioactive waste repositories

Safe disposal of nuclear waste in a geologic repository will rely on natural geologic features and engineered barriers to greatly retard the movement of radionuclides from the repository. Clay minerals including bentonite are effective in retarding the migration of many radionuclides, but are ineffective for anionic radionuclides, of which pertechnetate is of particular concern owing to its relatively long half-life and the lack of natural isotopes that dilute it. Activated carbon is proposed as an additive material for reducing pertechnetate mobility in the nearfield. Activated carbon materials of different origins quantitatively sorb pertechnetate from aqueous solution under oxidizing conditions during the first day of contact, and sequential extraction showed that 73 % of this technetium is in the strongly bound fraction. X-ray photoelectron spectra (XPS) and extended X-ray absorption fine structure (EXAFS) spectra both demonstrated that no reduction of technetium occurred in the studied systems. The interaction of technetium with a composite material consisting of bentonite and activated carbon was studied at the first time. Effective technetium sorption was shown, with distribution coefficients (Kd) up to 740 cm^3. g^-1.

Dataset on open/blind hole-hole interaction in barely visible impact damaged composite laminates

This dataset contains the mechanical properties and structural characteristics with images of the carbon fibre reinforced epoxy composite (CFRP) laminates with open/blind holes. The mechanical dataset are the fracture strength, strain at fracture, strain energy density for resilience, strain energy density to fracture and stiffness of the CFRP laminates for different setups (namely 1 hole, 2 holes parallel to applied load, and 2 holes normal to applied load) from pristine and barely visible impact damage (BVID) specimens, determine from in-plane compression test. The structural-related dataset include thermographs, images of BVID specimens, drilling-induced damage BVID specimens and video clips of crack propagation during in-plane compression testing.

Fire behavior of innovative alginate foams

A new biosourced composite foam (AF, associating foamed alginate matrix and orange peel filler) is successfully tested for fire-retardant properties. This material having similar thermal insulating properties and density than fire-retardant polyurethane foam (FR-PUF, a commercial product) shows promising enhanced properties for flame retardancy, as assessed by different methods such as thermogravimetric analysis (TGA), pyrolysis combustion flow calorimetry (PCFC) and a newly designed apparatus called RAPACES for investigating large-scale samples. All these methods confirm the promising properties of this alternative material in terms of fire protection (pHRR, THR, EHC, time-to-ignition, flame duration or production of residue), especially for heat flux not exceeding 50 kW m^-2. At higher heat flux (i.e., 75 kW m^-2), flame retardant properties tend to decrease but maintain at a higher level than FR-PUF. The investigation of the effect of AF thickness shows that the critical thickness (CT) is close to 1.5-1.7 cm: heat diffusion and material combustion are limited to the CT layer that protects the underlying layers from combustion. A multiplicity of factors can explain this behavior, such as: (a) negligible heat conduction, (b) low heat of combustion, (c) charring formation, and (d) water release. Water being released from underlying layers, dilutes the gases emitted during the combustion of superficial layers and promotes the flame extinction.

Calculating Filament Feed in the Fused Deposition Modeling Process to Correctly Print Continuous Fiber Composites in Curved Paths

Fused deposition modeling (FDM) is a popular additive manufacturing (AM) method that has attracted the attention of various industries due to its simplicity, cheapness, ability to produce complex geometric shapes, and high production speed. One of the effective parameters in this process is the filament feed presented in the production G-code. The filament feed is calculated according to the layer height, the extrusion width, and the length of the printing path. All required motion paths and filling patterns created by commercial software are a set of straight lines or circular arcs placed next to each other at a fixed distance. In special curved paths, the distance of adjacent paths is not equal at different points, and due to the weakness of common commercial software, it is not possible to create curved paths for proper printing. The creation of a special computer code that can be used to make various functions of curved paths was investigated in this study. The filament feed parameter was also studied in detail. Next, by introducing a correction technique, the filament feed was changed on the curved path to uniformly distribute the polymer material. Variable-stiffness composite samples consisting of curved fibers can be produced with the proposed method. The high quality of the printed samples confirms the suggested code and technique.

Modeling of adsorption flux in nickel-contaminated synthetic simulated wastewater in the batch reactor

In the present investigation, physico-chemical characterization of composite material revealed the presence of fluffy surface structure with crystalline look and negatively charged surface functional groups. The study of adsorption flux by using dimensionless numbers φ (2.62), N_k (62.68) and λ (1.17 × 10^-5) proved that adsorption of nickel ions on the surface of composite material was mostly film diffusion-limited with maximum surface area coverage coupled with weakened surface tension. The results of intraparticle diffusivity and Boyd plot model showed that at the onset of process, film diffusion was the primary mechanism involved and at the later stage intraparticle diffusion played a critical role as rate governing step. The values of film (0.65 × 10^-8 cm² sec^-1) and pore diffusivity (1.8 × 10^-12 cm² sec^-1) coefficients showed that the adsorption process is dependent upon two different types of diffusion namely film and pore diffusion. Overall, transport and reshuffling mechanism had no substantial role in adsorption dynamics of nickel ions on the surface of composite material. Sorption isotherm and kinetics modeling showed higher values of regression coefficients for Langmuir isotherm (R² = 0.99) and pseudo-second-order kinetic model (R² = 0.99) compared to other models. This showed that sorption of nickel followed monolayer coverage with chemisorption at optimized process parameters like pH 6, biosorbent dose 0.1 g/L, temperature 50 °C, agitation rate180 rpm, adsorbate concentration100 mg/L and contact time 60 minutes. The positive value of enthalpy of adsorption (ΔH = + 10.41 kJ/mole) and entropy (ΔS = +58.19 J/mol K) showed that binding of nickel ions on the surface of the composite material was endothermic with improved randomness at solid-liquid interface. The negative value of (ΔG = -6.4 to -8.67 kJ/mol) showed spontaneous nature of nickel adsorption on composite material in the liquid phase.

Experimental and optimised data set for hot extrusion of B4C/Al 6061 composite using Taguchi coupled GRA technique

Modern aluminium composites reinforced with variety of hard particles become more usage in Industrial environment. But manufacturing of composites with homogenously distributed reinforcement becomes the challenge. To overcome this challenge, most of the Aluminium composite are undergone a secondary extrusion process. The data presented here are related to hot extrusion of round geometry to hexagonal section Al/B₄C composite. Availability of data is extended to expose the optimal parameters of the process over the extrusion load and tensile strength of the extrudate. Ram speed, geometry of die profile, billet temperature and friction within the die and billet interface have been considered as chief process parameters which influence the extrusion load and strength of the product. Totally, nine experiments were conducted as per Taguchi's L9 orthogonal array to reach optimal parameters. Most influencing parameters with ranking significance have been arrived through ANOVA, MRPI and grey grade. Optimal parameters were compared with confirmation experiments and predicted one to justify the investigation

Uncoiling springs promote mechanical functionality of spider cribellate silk

Composites, both natural and synthetic, achieve novel functionality by combining two or more constituent materials. For example, the earliest adhesive silk in spider webs - cribellate silk - is composed of stiff axial fibers and coiled fibers surrounded by hundreds of sticky cribellate nanofibrils. Yet, little is known of how fiber types interact to enable capture of insect prey with cribellate silk. To understand the roles of each constituent fiber during prey capture, we compared the tensile performance of native-state and manipulated threads produced by the cribellate spider Psechrus clavis, and the adhesion of native threads along a smooth surface and hairy bee thorax. We found that the coiled fiber increases the work to fracture of the entire cribellate thread by up to 20-fold. We also found that the axial fiber breaks multiple times during deformation, an unexpected observation that indicates: (i) the axial fiber continues to contribute work even after breakage, and (ii) the cribellate nanofibrils may perform a previously unidentified role as a binder material that distributes forces throughout the thread. Work of adhesion increased on surfaces with more surface structures (hairy bee thorax) corresponding to increased deformation of the coiled fiber. Together, our observations highlight how the synergistic interactions among the constituents of this natural composite adhesive enhance functionality. These highly extensible threads may serve to expose additional cribellate nanofibrils to form attachment points with prey substrata while also immobilizing prey as they sink into the web due to gravity.

[Advances in the research of antibacterial properties and composite materials of nanometer zinc oxide]

Nanometer zinc oxide has become a new hotspot in the research of tissue engineering materials due to its excellent antibacterial properties, biocompatibility, and anti-tumor properties. In this paper, the existing research results were summarized, generalized, and analyzed. The antibacterial mechanism of nanometer zinc oxide was discussed in depth. The antibacterial properties and advantages of the latest nanometer zinc oxide composite materials were introduced in detail. In this review, we made prospect of the future application of nanometer zinc oxide.

Measurement of velocity and attenuation of ultrasonic guided wave for real-time estimation of cure-dependent anisotropic viscoelastic properties of carbon fiber-reinforced plastics

An ultrasonic guided wave-based cure monitoring technique is developed to estimate cure-dependent anisotropic viscoelastic properties of carbon fiber reinforced plastics (CFRPs). The guided wave propagating in the transverse direction of a CFRP was measured during a cure process and the energy velocity and attenuation were obtained by signal processing. A micromechanics model and transfer matrix method were used to express the energy velocity and attenuation as functions of only the complex Young's modulus of the resin. The complex Young's modulus of the resin was estimated from the measurement results using response surfaces of the relationship between the energy velocity, attenuation and the resin complex modulus. It was verified that the estimated storage modulus and loss modulus showed reasonable values and behavior. The development of the anisotropic viscoelastic property of CFRPs can be fully determined in real time using this technique.

Dissolution, bioactivity and osteogenic properties of composites based on polymer and silicate or borosilicate bioactive glass

Bioactive glass (BAG)/Poly (Lactic Acid) (PLA) composites have great potential for bone tissue engineering. The interest in these materials is to obtain a scaffold with tailorable properties bringing together the advantages of the composites' constituents such as the biodegradability, bioactivity and osteoinduction. The materials studied are PLA/13-93 and PLA/13-93B20 (20% of SiO₂ is replaced with B₂O₃ in the 13-93 composition). To characterize them, they were dissolved in TRIS buffer and Simulated Body Fluid (SBF) in vitro. Over the 10 weeks of immersion in TRIS, the ion release from the composites was constant. Following immersion in SBF for 2 weeks, the hydroxyapatite (HA) layer was found to precipitate at the composites surface. By adding Boron, both these reactions were accelerated, as the borosilicate glass dissolves faster than pure silicate glass alone. Polymer degradation was studied and showed that during immersion, the pure PLA rods maintained their molecular weight whereby the composites decreased with time, but despite this the mechanical properties remained stable for at least 10 weeks. Their ability to induce osteogenic differentiation of myoblastic cells was also demonstrated with cell experiments showing that C2C12 cells were able to proliferate and spread on the composites. The Myosin Heavy Chain and Osteopontin were tracked by immunostaining the cells and showed a suppression of the myosin signal and the presence of osteopontin, when seeded onto the composites. This proves osteoinduction occurred. In studying the mineralization of the cells, it was found that BAG presence conditions the synthesizing of mineral matter in the cells. The results show that these composites have a potential for bone tissue engineering.

Natural rubber/reduced-graphene oxide composite materials: Morphological and oil adsorption properties for treatment of oil spills

•

Natural rubber/rGO composite foam was used as an oil sorbent.

•

Addition of rGO enhanced the oil adsorption capacity and strength of NR sorbent foam.

•

Inclusion of 0.5 phr rGO into NR increased the crude oil adsorption capacity to 17.04 g g⁻¹.

•

Oil adsorption mechanism of the sorbent materials was proposed.

•

Reusability of the NR/rGO sorbent was greater than 70% oil adsorption for 30 cycles.

A green sorbent material was fabricated through the simple addition of reduced graphene oxide (rGO) to natural rubber (NR) latex. The effect of rGO content in the NR foam on petroleum oil adsorption was investigated. The addition of rGO in NR increased the petroleum oil adsorption capacity of the resulting NR/rGO (NRG) composite foam (12–21 g g⁻¹) with respect to those of the pure NR foam (8–15 g g⁻¹) and a commercial sorbent (6–7 g g⁻¹). The adsorption capacity was optimal for 0.5 phr rGO (NRG-0.5). Further, the environmental conditions (temperature and waves) affected the oil adsorption capacity of the sorbent materials. The adsorption kinetics of the sorbent materials for crude AXL oil was best described with pseudo-second-order kinetics. The interparticle diffusion model revealed three steps whereas the adsorption isotherms approximated the Langmuir isotherms. Moreover, the oil adsorption mechanisms of the NR and NRG sorbent materials were compared to that of a commercial sorbent. The high elasticity of the NRG-0.5 composite foam improved not only the oil adsorption capacity but also the reusability of the sorbent material. The presence of rGO increased the strength of the NRG-0.5 compared to that of pure NR, which resulted in a high-performance and reusable material with an oil removal efficiency higher than 70% after 30 uses.

Sinusoidal voltage electrodeposition of PEDOT-Prussian blue nanoparticles composite and its application to amperometric sensing of H2O2 in human blood

A selective electrochemical sensor based on poly(3,4-ethylenedioxythiophene) (PEDOT) - Prussian blue nanoparticles (PBNPs) for hydrogen peroxide (H₂O₂) determination was prepared by innovative sinusoidal voltage (SV) method. The successful incorporation of citrate-stabilized PBNPs into PEDOT matrix was confirmed by energy dispersive X-ray analysis (EDX), Raman spectroscopy, UV-Vis spectroelectrochemistry and cyclic voltammetry measurements. The SV preparation method provides a PEDOT-PBNPs coating with rough surface morphology and good electrocatalytic activity toward H₂O₂ reduction. The amperometric response of PEDOT-PBNPs-based sensor at -50 mV vs. Ag/AgCl is linear within the range of concentrations from 5 μM to 1 mM H₂O₂ with a detection limit of 1.4 μM H₂O₂. The proposed Pt/PEDOT-PBNPs sensor displays good repeatability, reproducibility, operational stability as well as good selectivity toward H₂O₂ determination in the presence of interfering species like dopamine (DA), uric acid (UA), KNO₂ glucose (Glu), KNO₃ and ascorbic acid (AA), and was successfully applied to H₂O₂ determination in human blood samples without biofouling.